In a meta-analysis of 135 studies involving 6000 patients with Alzheimer's disease (AD) and 6057 healthy controls, we examined the relative degree of semantic and phonemic fluency impairment in AD patients. The effect size for semantic fluency (d=2.10: 95%CI 2.22-1.97) was significantly larger than for both phonemic fluency (d=1.46: 95%CI 1.56-1.36) and picture naming (d=1.54: 95%CI 1.66-1.40). In meta-regression analyses we found that studies with greater proportions of female patients and less severe dementia both led to better phonemic fluency; while perhaps surprisingly, increased patient education led to worse semantic fluency. Critically, in 50 studies measuring both semantic and phonemic fluency, the effect size for the semantic-phonemic discrepancy scores did not differ between AD patients and controls; and was unrelated to any of the moderator variables. The latter findings indicate that the semantic-phonemic fluency discrepancy measure often reported as an important distinguishing characteristic of AD patients may be an exaggerated normal tendency.

Authors:

Keith R Laws; Amy Duncan; Tim M Gale

Publication Detail:

Type:
Journal Article; Meta-Analysis
Date:
2009-05-18

Journal Detail:

Title:
Cortex; a journal devoted to the study of the nervous system and behavior
Volume:
46
ISSN:
1973-8102
ISO Abbreviation:
Cortex
Publication Date:
2010 May

Date Detail:

Created Date:
2010-03-15
Completed Date:
2010-06-02
Revised Date:
-

Medline Journal Info:

Nlm Unique ID:
0100725
Medline TA:
Cortex
Country:
Italy

Other Details:

Languages:
eng
Pagination:
595-601
Citation Subset:
IM

Copyright Information:

Copyright 2009 Elsevier Srl. All rights reserved.

Affiliation:

School of Psychology, University of Hertfordshire, Hatfield, UK. k.laws@herts.ac.uk